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Thomas Staubo
10-18-2007, 12:39 PM
I'm planning on getting a new compressor, and I wonder if there is an advantage in getting one with a belt drive, regarding noise (or other aspects).
I have looked at 50 liter - 3HP - V-twin types.

I didn't find much in the archives, but some mentioned a lot of the noise is from the intake(s), and could be muffled or routed to the outside. Anybody got an idea for muffling?
I don't like much noise in the garage.

Also what is a two-stage compressor (these are not)?
Is that a feature of larger compressors maybe.

Thank you!

Example:
http://www.clasohlson.no/Archive/Images/Products/Hi/309563_X_2006-06-29_095441_105.jpg

ahidley
10-18-2007, 12:49 PM
Belts are the way to go because when the motor goes bad you can replace it with a standard one. Without a belt you need to go back to the origonal manufacturer.

A 2 stage uses one cylinder to fill the other cylinder, thus compressing it twice. result is higher pressure, drawback is less volume.

chipmaker4130
10-18-2007, 12:49 PM
Hello Thomas. Belt-drive compressors, as a rule are much quieter than the direct-drive diaphragm type. It is not so much the drive as the pump style that makes the difference. A two-stage pump brings in air, compresses it, feeds it to another cylinder which compresses it more, then sends it to the tank. There is no benefit to this type of action in the size compressor you are looking at (my opinion). A twin cylinder single stage pump like the one in your picture is a great way to go. Moving the intake and filter outside your garage will reduce noise to some degree.

Mosside
10-18-2007, 01:02 PM
Lots of good useful information on compressors here:http://www.practicalmachinist.com/ubb/ultimatebb.php/topic/8/39.html

Thomas Staubo
10-18-2007, 02:43 PM
Thanks guys!

At the link you gave me Mosside, the "expert" said:

"Compressors divide neatly into oilless and belt driven."
That's surely a false statement.
Well, most of the home shop compressors I've seen (15-50 liters) are directly coupled AND oil lubricated. Then from 50l and up belt drive is the more common.

So, I don't believe 100% anymore that belt drive is less noisy (because most people think that direct-coupled =oilless), unless you have some personal experience with both types (belt vs direct drive).

Advantages to belt drive as I see it (AFAIK):
1. Easier to replace motor and/or cylinder when needed
2. The ratio between motor and cylinder can be altered if needed.
3. Motor may be replaced with larger one.

One thing I haven't thought about is that lower revs are a good thing, regarding to both noise and longevity.

How about cylinder material? I suspect cheaper compressors have aluminium cylinders, is that a negative?

Joel
10-18-2007, 02:51 PM
One thing I haven't thought about is that lower revs are a good thing, regarding to both noise and longevity.
Correct on both counts.


How about cylinder material? I suspect cheaper compressors have aluminium cylinders, is that a negative?
Yes. Cast Iron is typically regarded as the material of choice.

tattoomike68
10-18-2007, 02:53 PM
If noise is an issue you can build a little dog house and keep it outside.

I have a shed on the back of my garage and thats where I plan on putting one when I get it.

jimmstruk
10-18-2007, 02:59 PM
Thomas, I am more of a mechanic than a machinist, so my opinion may or may not impress you. First if you use an impact wrench much, the extra pressure made by a 2 stage is very neccesary. There are many very old compressors still going strong that were built with cast iron cylinders. If you dont need the pressure a single stage unit is less expensive. Only you can know your needs. JIM

Thomas Staubo
10-18-2007, 03:04 PM
Belt-drive compressors, as a rule are much quieter than the direct-drive diaphragm type. It is not so much the drive as the pump style that makes the difference.
I didn't read that line properly until now, and I'm a little surprised, when you mention diaphragm compressors as noisy.
I think most of the cheaper oilless compressors are piston type.
If I were rich, I would have bought a compressor made by Jun-Air (http://www.jun-air.com/), they are diapragm type, and are VERY silent. They come in many variants, with from one to six compressor heads on one tank, both in oil and oilless varieties. Many are used in health care and laboratories. But here are an assortment for normal applications (oiled type):
http://www.allair.com/images/JunAirOil.jpg

Bguns
10-18-2007, 04:01 PM
Thomas
As is typical ...The europeans have a better design diaphram compressor, but also not cheap.....

Our cheap Home grade Oilless compressors sound about like a pavement breaker/Jackhammer and are loud enough to require earplugs...

A LOT of noise for very little air.

motomoron
10-23-2007, 03:53 PM
Having owned a long succession of Compressors I Hated, I offer the following advice:

Go big! - There's no such thing as too much air. If there's a remote possibility you might ever want to run even a small bead blast cabinet, disc grinder, sand blaster, or HVLP spray guns, get something 2 cylinder if not 2 stage, 5 actual HP or better, and 60 gallon tank if you have room.

Cast iron is a good material for compressor pumps.

Get a big water trap and decent regulator. I have a Sharpe with connections pre-and post regulator.

Really dry air comes from an air dryer. After I got a plasma cutter, I ended up with a refrigerated air dryer.

Deals are out there if you're patient. I got a very nice 60 gallon/5hp/2 stage Speedair, a matching refrigerated air dryer, and all the copper pipe, fittings and ball valves for a comprehensive air system all for about $750 on the local Craigslist over a period of about 6 months.

Note that I didn't mention "oilless" compressors. I've had my fill of disassembling and repairing sh1tty Campbell-Hausfeld oilless compressors while the paint on a half sprayed set of motorcycle bodywork flashes off.

They're deafeningly loud, they vibrate and shake themselves apart, overspray clogs the fragile reed valves, and a few weekend of all day use constitutes what the manufacturer views as a liftime of "consumer' use.

Spare yourself the agony and expens and do it right one time rather than chipping away at the problem for 15 years 'til you finally get a good one.

BTW, I just got the compressor for the shop here at work: 15 year old lightly used Speedaire 5hp/2 stage/80 gallon/3 phase industrial machine for $400 with an easy 15 years left in it.